Non-destructive testing for mechanical components in nuclear island of nuclear power plants - Part 2: Ultrasonic testing
1 Scope
This part of NB/T 20003 specifies:
——general technical requirements for ultrasonic testing, and relevant supplementary requirements and acceptance criteria for specific types of workpieces;
——technical requirements for measuring workpiece thickness by ultrasonic pulse-echo contact method.
This part is applicable to ultrasonic testing of raw materials and parts such as castings, sheets, forgings, pipes and bars of mechanical components in nuclear island of nuclear power plants, as well as welded joints, isolation layers, surfacing layers, composite plates and other materials during the fabrication and installation process.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 12604.1 Non-destructive testing - Terminology - Terms used in ultrasonic testing (GB/T 12604.1-2005, ISO 5577: 2000, IDT)
GB/T 19799.1-2005 Non-destructive testing - Ultrasonic testing - Calibration block No.1 (ISO 2400: 1972, IDT)
GB/T 19799.2-2005 Non-destructive testing - Ultrasonic testing - Calibration block No.2 (ISO 7963: 1985, IDT)
JB/T 8428-2006 Non-destructive testing - Blocks for ultrasonic testing
JB/T 9214-1999 Practice for evaluating performance characteristics of A scope ultrasonic pulse-echo testing systems
JB/T 10061-1999 Commonly used specification A-mode ultrasonic flaw detector using pulse echo technique
JB/T 10062-1999 Testing methods for performance of probes used in ultrasonic flaw detection
NB/T 20003.1-2010 Non-destructive testing for mechanical components in nuclear island of nuclear power plants - Part 1: General requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions established in GB/T 12604.1 and NB/T 20003.1-2010 and the following apply.
3.1
probe shoe
certain shape of material block inserted between the probe and the test object to improve coupling or protect the probe
3.2
wedge
special wedge piece that is placed between the transducer and the test object and can refract the ultrasonic beam at a given angle into the test object in case of acoustic contact with the above two
Note: it is commonly made of engineering plastics.
3.3
transducer
active component of the probe that can convert electrical energy into ultrasonic energy or vice versa
Note: it is also called crystal.
3.4
nominal angle of probe
refraction angle of probe indicated by a given material and temperature
3.5
nominal frequency
frequency of the probe indicated by the manufacturer
3.6
centre frequency
arithmetic average value of the corresponding frequency when the amplitude is 6dB lower than that of the peak frequency during the testing by pulse echo method
3.7
squint angle
the squint angle of the normal probe is the angle between the geometric axis of the probe and the main beam axis
The squint angle of the angle probe is the angle between the geometric axis of the probe and the projection of the main beam axis on the test surface.
3.8
standard block
material block with specified chemical composition, surface roughness, heat treatment and geometric shape, which is used to evaluate and calibrate ultrasonic testing equipment
3.9
reference block
test block with the same or similar material or chemical composition and the same or similar acoustic characteristics as the test object, and a specific reflector, which is used to adjust the sensitivity or time base range of ultrasonic testing equipment and compare the detected discontinuous signals with signals generated by known reflectors
3.10
reflector
an interface at which an ultrasonic beam encounters a change in acoustic impedance
3.11
time base range
ultrasonic path length that is displayed on a particular time base
3.12
creeping wave
wave generated at the first critical angle of incidence and propagated along the surface of the medium as a longitudinal wave
Note: Its sound velocity is basically equivalent to that of longitudinal wave.
3.13
DGS diagram
a series of curves describing the relationship between distance, echo amplitude (gain) and equivalent size of regular reflectors
Note: The X-axis usually represents the distance, while Y-axis represents the echo amplitude or gain. It is also known as AVG diagram.
3.14
DGS method
method of characterizing the equivalent size of the to-be-evaluated reflector by the diameter of the disc-shaped reflector with the same echo height as the to-be-evaluated reflector, using DGS diagram
Note: it is also known as AVG method.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General requirements
4.1 Testing personnel
4.2 Testing documents
4.3 Testing range
4.4 Verification of procedures
5 Apparatus
5.1 Ultrasonic flaw detector
5.2 Probe
5.3 Coupling medium
5.4 Test blocks
5.5 Performance test
6 Testing conditions
6.1 Testing time
6.2 Testing area
6.3 Test surface
6.4 Surface preparation
6.5 Accessibility
6.6 Requirements for environment conditions
6.7 Test object
7 System calibration and recalibration
7.1 General requirements
7.2 Recalibration during testing
7.3 Precautions
8 Testing techniques
8.1 Scope
8.2 Normal beam wave testing and angle beam wave testing
8.3 Contact method and immersion method
8.4 Special techniques or new techniques
9 Testing
9.1 Scanning
9.2 Adjustment of time base range
9.3 Adjustment of sensitivity
9.4 Sensitivity compensation
9.5 Determination of indication
10 Evaluation
11 Acceptance
12 Castings
12.1 Scope
12.2 General requirements
12.3 Testing time
12.4 Testing area
12.5 Scanning
12.6 Reference block
12.7 Detectability evaluation
12.8 DAC curve
12.9 Supplementary testing
12.10 Record
12.11 Evaluation and quality grade
12.12 Acceptance criteria
13 Sheets
13.1 Scope
13.2 General requirements
13.3 Testing technique
13.4 Probe
13.5 Reference block
13.6 Testing time
13.7 Scanning
13.8 Basic sensitivity
13.9 Measurement of loss of back echo
13.10 Measurement of record of indications
13.11 Evaluation
13.12 Quality grade
13.13 Acceptance criteria
14 Forgings
14.1 Scope
14.2 General requirements
14.3 Classification of forgings
14.4 Apparatus
14.5 Test conditions
14.6 Testing
14.7 Evaluation and quality grade
14.8 Acceptance criteria
15 Forged and rolled bars
15.1 Scope
15.2 General requirements
15.3 Testing time
15.4 Reference block
15.5 Probe
15.6 Testing
15.7 Sensitivity
15.8 Record
15.9 Quality grade and acceptance criteria
16 Bolt materials
16.1 Scope
16.2 General requirements
16.3 Reference block
16.4 Probe
16.5 Testing time
16.6 Scanning
16.7 Sensitivity
16.8 Record
16.9 Quality grade and acceptance criteria
17 Pipes
17.1 Scope
17.2 General requirements
17.3 Testing time
17.4 Testing area
17.5 Testing technique
17.6 Probe
17.7 Coupling medium
17.8 Scanning method
17.9 Reference block
17.10 Automatic testing equipment
17.11 Calibration and recalibration
17.12 Additional requirements for automatic testing
17.13 Determination of indication
17.14 Record and acceptance criteria
18 Full penetration welded joints
18.1 Scope
18.2 General requirements
18.3 Testing conditions
18.4 Testing
18.5 Record and acceptance criteria
18.6 Testing of repair welding zone
19 Isolation layers, surfacing layers and composite plates
19.1 Scope
19.2 General requirements
19.3 Testing conditions
19.4 Reference block
19.5 Testing
19.6 Record and acceptance criteria
19.7 Testing of repair welding zone
20 Thickness measurement by ultrasonic pulse-echo contact method
20.1 Scope
20.2 General requirements
20.3 Apparatus
20.4 Testing conditions
20.5 System calibration and recalibration
20.6 Measuring method
20.7 Measurement
20.8 Records and reports of thickness measurement
21 Testing report and record
21.1 Testing report
21.2 Testing records
Annex A (Normative) Screen height linearity
Annex B (Normative) Testing of horizontal linearity and vertical linearity
Annex C (Informative) Method for ultrasonic shear wave testing of steel castings
Annex D (Informative) Ultrasonic shear wave circumferential scanning for forgings
Annex E (Informative) Scanning of key forgings
Annex F (Informative) Determination and calculation of attenuation coefficient of workpiece material
Annex G (Informative) Ultrasonic testing of the centrifugal casting austenite main piping
Annex H (Informative) Ultrasonic testing of dissimilar metal welded joints
Annex I (Informative) Plotting of outline drawing at welded joint
Annex J (Informative) Judgment of flaw nature
